We plan to carry on our studies concerning the regulation of the IgE immune response. 1- Genetic control and regulation of the IgE reaginic antibody production. We are presently studying a possible linkage of the high IgE response with a known gene. This study aims at the discovery of criteria which would permit to detect humans with high risks of sensitization. We also plan to study the physiological mechanism(s) which stop(s) the IgE reaginic immune response. We use the radiation-induced enhancement model of the IgE immune response which we have developed. We hope to find a method by which to stop the reaginic immune responses in allergic patients. 2- Role of antibodies and in particular of IgE reaginic antibodies in the defense of organisms of rats against bacterial and parasitic diseases. Using immunodeficient rats (athymic or neonatally mu-suppressed animals) we shall study the different cellular (macrophage, eosinophil, mast cell etc.) or humoral (antibodies of different isotypes) parameters of the defense mechanisms against parasites. 3- Rat myeloma tumor incidence. We shall pursue our studies of the genetic control of the rat myeloma tumors which is the only experimental model of such cancer.